CN101944878B - Induction motor parameter identification - Google Patents

Abstract

A method and an arrangement are provided for identifying parameters of an induction machine when the induction machine is connected to the output phases of a voltage source inverter and the induction machine is in standstill state. The method includes providing a DC magnetization current (idc_magn) to the induction machine with the inverter, controlling the power semiconductors of the inverter to an off-state, controlling all the output phases of the inverter to the same potential to provide a zero voltage vector, measuring the stator current (isd) during the zero voltage vector, and determining parameters of the induction machine from the stator current (isd) measured during the zero voltage vector.

Description

Induction motor parameter identification

Technical field

The present invention relates to a kind of method of identifying the parameter of electric machine, more specifically, relate to and a kind ofly can identify the method for the parameter of induction machine in the non-rotary situation of motor.

Background technology

When frequency of utilization transducer or like device control motor rotation, it is known needing the parameter of electric machine.Need the parameter of electric machine in the control algolithm of transducer, be used for control load exactly.Can identify the parameter of electric machine with identifying between the trial run period of driver.In this identifying operation, transducer is carried out one or more tests and is estimated required parameter for controlling motor.

In some cases, the load that is connected to motor has caused some restrictions for driver, thereby can not carry out identifying.The load that is connected to the motor of controlling has produced countertorque, and this countertorque upsets identifying operation, to such an extent as to identifying can not provide the accurate result of the accurate control that realizes motor.Also following situation may appear: due to maximum speed limit and/or the breakdown torque limit for load set, can not carry out identifying operation by bringing onto load fully.In these cases, identifying operation breaks away from motor and the load controlled needs fully.This is usually trouble, and if motor to be controlled is the part of the mechanical structure of load, sometimes or even impossible.

For these purposes, frequency converter can have the option about the stall identifying, and wherein the rotor of motor does not rotate.Yet stalling only can be identified some parameters of electric machine, and other parameter is to use the rated value of motor to calculate.

Fig. 1 shows inductance (L) equivalent electric circuit of induction machine.Use by constant stator voltage u _sThe DC magnetizing current that produces, i.e. stator current i _s, can identify easily the stator resistance R of equivalent electric circuit _sUse has the summation pulse current or has the DC electric current of certain other Injection Currents, can identify rotor resistance R _RWith stray inductance σ L _s

The problem relevant to known stall recognition methods be, because motor can not rotate, so main inductance L _MAnd the rotor time constant τ that depends on main inductance _r(=L _M/ R _R) measurement be very thorny.This is owing to the following fact: in the stall method, the stator current pulse with phase place opposite with rotor current of using is almost sued for peace fully.This means magnetizing current i _mCorresponding change be relatively little, therefore and be poor from the response to test pulse of main inductance.

Known stall method can not obtain the gratifying valuation about main inductance and rotor time constant, and these parameters normally obtain from slip frequency and power factor are approximate, and this slip frequency and power factor are from the rated value of motor or from the cos θ value that provides as rated value and calculating.On the other hand, these rated values not necessarily accurately, thereby the value about main inductance and rotor time constant that obtains by known stall recognition methods is inaccurate, the performance that the parameter that obtains in the identifying operation that utilizes execution when motor rotate realizes, this reflects worse control performance.

The accuracy of voltage measurement should greatly increase, thereby can calculate about main inductance L in the stall method _MOr rotor time constant τ _rValuation fully accurately.Owing to typically making up output voltage in the calculated rate transducer with measured DC bus voltage and output switch for the purpose of Cost reduction, so the increase of voltage accuracy is difficult to realize.In this type of was measured, commutation postponed and threshold voltage has caused the inaccurate of voltage measurement.Than the voltage response from the main inductance under injected frequency (injection frequency), these are inaccurate may be very significant.

Summary of the invention

The object of the present invention is to provide a kind of method and a kind of device be used to realizing the method, so that address the above problem.The objective of the invention is to realize by the method and apparatus with feature of setting forth in independent claims.The preferred embodiments of the present invention are disclosed in dependent claims.

The present invention is based on the thinking of the decay counter voltage of indirect measurement induction machine.By method and apparatus of the present invention, can identify required parameter for controlling induction machine in the non-rotary situation of motor.

Method and apparatus of the present invention in the situation that need not increases the voltage measurement accuracy and has eliminated inaccurate relevant the problems referred to above to estimated main inductance and rotor time constant.The invention provides a kind of method of directly determining rotor time constant, if after this rotor resistance is known, can also estimate main inductance.Embodiments of the invention also provide a kind of method for determining rotor resistance.In addition, embodiments of the invention also provide a kind of for than the method for calculated threshold voltage more accurately in the past.

Description of drawings

By means of preferred embodiment, the present invention is described in more detail with reference to the accompanying drawings hereinafter, in the accompanying drawings:

Fig. 1 shows the equivalent electric circuit of induction machine;

Fig. 2 shows stator current in embodiments of the invention and the waveform of rotor flux;

Fig. 3,4,5 and 6 shows the waveform of the stator current in embodiments of the invention;

Fig. 7 shows the waveform of the magnetizing current in embodiments of the invention;

Fig. 8 shows the waveform of the stator current in another embodiment of the present invention;

Fig. 9 shows the waveform of the stator current in embodiments of the invention and the waveform of rotor flux; And

Figure 10 shows be used to the example of implementing control system of the present invention.

Embodiment

In the following description, at first use method of the present invention to determine rotor time constant, provided subsequently the description of estimated rotor resistance and threshold voltage about how.In further describing, in the situation that determine rotor time constant with other cache oblivious ground of induction machine, used the present invention, and provided at last about the description from the result calculating main inductance by method acquisition of the present invention.The description here also comprises the example be used to the control system of the frequency converter of implementing method of the present invention.

Rotor time constant

The present invention is based on following thinking: inactive when the power stage that makes frequency converter when motor is magnetized, that is, mains switch is controlled to be in the situation of off status, indirectly measure the decay counter voltage of induction machine.Before the power stage passivation that makes frequency converter or frequency converter, the magnetization of motor is performed, makes the magnetic flux of motor be in stable state.According to the present invention, provide the DC magnetization by frequency converter to induction machine, and the power semiconductor of frequency converter is controlled to be off status.

After following the power stage passivation closely, stator current commutates to the fly-wheel diode that is connected with the switch inverse parallel of controlling in the short period.Owing to there being voltage in motor terminal, the dc voltage that this voltage equals to use and having with respect to the opposite polarity of stator current (as long as diode loaded current), so current vector is rapidly reduced to zero.Current attenuation typically continues 200 to 300 μ s and rotor flux to zero and can greatly not descend during this period.

When electric current reached zero, the value of rotor flux was:

ψ _R＝L _Mi _{dc_magn}＝R _Rτ _ri _{dc_magn} (1)

I wherein _{Dc_magn}To be fed to the magnetizing current of motor before making the power stage passivation.

After supposing passivation, at moment t=t ₀Electric current has dropped to zero.After this moment, the rotor flux of motor is pressed timeconstantτ according to following index law _rDecay:

${\mathrm{\ψ}}_R\left(t\right)={\mathrm{\ψ}}_R{e}^{-t(t-t_0)/{\mathrm{\τ}}_r}=L_M{i}_{\mathrm{dc}\_\mathrm{magn}}{e}^{-(t-t_0)/{\mathrm{\τ}}_r}=R_R{\mathrm{\τ}}_r{i}_{\mathrm{dc}\_\mathrm{magn}}{e}^{-\left(t{-t}_0\right)/{\mathrm{\τ}}_r}---\left(2\right)$

The decay of rotor flux has been inducted for the voltage of motor terminal, can use the dynamical equation of following motor to calculate this voltage:

$u_{\mathrm{sd}}=(R_s+R_R)i_{\mathrm{sd}}+\mathrm{\σ}{L}_s\frac{{\mathrm{di}}_{\mathrm{sd}}}{\mathrm{dt}}-\frac{{\mathrm{\ψ}}_R}{{\mathrm{\τ}}_r}---\left(3\right)$

U wherein _sdAnd i _sdStator voltage component and the stator current component on the direction of rotor flux and magnetizing current.

Because the derivative of electric current and electric current is zero, therefore according to (3):

$u_{\mathrm{sd}}=-\frac{{\mathrm{\ψ}}_R}{{\mathrm{\τ}}_r}---\left(4\right)$

Therefore the instantaneous voltage in electrode terminal is directly proportional to the value of rotor flux.Therefore, when rotor flux was decayed, stator voltage decayed according to same index law.By measuring two not in the same time terminal voltages of motor, will basically can determine rotor time constant.The voltage of equation (4) is low (typically less than 10V), to such an extent as in the situation that do not have expensive special device can not measure these voltages in frequency converter.

In the present invention, solved this problem by indirectly measuring the described moment.According to the present invention, all outputs of frequency converter are controlled as same current potential mutually, are used for providing zero-voltage vectors.So the power stage of frequency converter is activated and all export the positive or negative dc voltage that is controlled as mutually intermediate circuit, for generation of null vector.Due to the diode of power stage and transistorized threshold voltage less than induced voltage (4), the threshold voltage u that therefore equals to play a role on power semiconductor when the terminal voltage of motor _thThe time, stator current begins to flow.

u _sd＝-u _th (5)

When using zero-voltage vectors, electric current is followed equation:

${-u}_{\mathrm{th}}=(R_s+R_R)i_{\mathrm{sd}}+\mathrm{\σ}{L}_s\frac{{\mathrm{di}}_{\mathrm{sd}}}{\mathrm{dt}}-\frac{{\mathrm{\ψ}}_R}{{\mathrm{\τ}}_r}---\left(6\right)$

As shown in Figure 2, thus electric current by time constant σ L _s/ (R _s+ R _R) rise on the direction of original magnetizing current, this time constant is than rotor time constant τ _r=L _M/ R _RLittle a lot.After the specific time, electric current reaches its maximum i _{Sdz_max}, after this still decays due to rotor flux and force the derivative of the electric current in equation (6) finally to be born, so electric current begins to descend again.

In Fig. 2, electric current is at moment t=t _zHaving its maximum, is zero at the derivative of this moment electric current:

${\left(\frac{{\mathrm{di}}_{\mathrm{sd}}}{\mathrm{dt}}\right)}_{t=t_z}=0---\left(7\right)$

In the moment of electric current maximum, cancellation stray inductance item from equation (6).Therefore, at moment t _z, equation (6) can be written as:

$-u_{\mathrm{th}}=(R_s+R_R)i_{\mathrm{sdz}\_\max }-\frac{{\mathrm{\ψ}}_R\left(t_z\right)}{{\mathrm{\τ}}_r}---\left(8\right)$

Moment t _zThe value of rotor flux depend on as follows the maximum i of electric current _{Sdz_max}And rotor time constant:

ψ _R(t _z)＝(u _th+(R _s+R _R)i _{sdz_max})τ _r (9)

If suppose at moment t _zBefore, can greatly the not slow down decay of rotor flux of the increase of the stator current during null vector, the index law of equation (2) should produce the value of the basis (9) about rotor flux.In other words:

${\mathrm{\ψ}}_R\left(t\right)=R_R{\mathrm{\τ}}_r{i}_{\mathrm{dc}\_\mathrm{magn}}{e}^{-\left(t_z{-t}_0\right)/{\mathrm{\τ}}_r}=-(u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{sdz}\_\max }){\mathrm{\τ}}_r---\left(10\right)$

Can solve rotor time constant from equation (10) as follows now:

$e^{-(t_z-t_0)/{\mathrm{\τ}}_r}=\frac{u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{sdz}\_\max }}{R_R{i}_{\mathrm{dc}\_\mathrm{magn}}}$

$\&DoubleRightArrow;{\mathrm{\&tau;}}_r=\frac{t_z-{\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">t</figure-callout>}}_0}{\ln \left(\frac{R_R{i}_{\mathrm{dc}\_\mathrm{magn}}}{u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{sdz}\_\max }}\right)}---\left(11\right)$

By only (namely arriving t between the active period of null vector _z0) use index law and by calculating subsequently the change from the rotor flux of stator current, can consider because of period t _z0... t _zThe error that obtains in the valuation of the decay of the rotor flux that the increase of stator current during this time causes and equation (11):

${\mathrm{\&psi;}}_R\left(t_z\right)=R_R{\mathrm{\&tau;}}_r{i}_{\mathrm{dc}\_\mathrm{magn}}{e}^{-(t_z-t_0)/{\mathrm{\&tau;}}_r}+\frac{1}{{\mathrm{\&tau;}}_r}\underset{t_{z0}}{\overset{t_z}{\&Integral;}}(L_M{i}_{\mathrm{sd}}\left(t\right)-{\mathrm{\&psi;}}_R\left(t\right))\mathrm{dt}---\left(12\right)$

$=R_R{\mathrm{\&tau;}}_r{i}_{\mathrm{dc}\_\mathrm{magn}}{e}^{-(t_z-t_0)/{\mathrm{\&tau;}}_r}+\underset{t_{z0}}{\overset{t_z}{\&Integral;}}(R_R{i}_{\mathrm{sd}}\left(t\right)-\frac{{\mathrm{\&psi;}}_R\left(t\right)}{{\mathrm{\&tau;}}_r})\mathrm{dt}$

At period t _z0... t _zComponent of voltage ψ in integration during this time _R/ τ _rValue can be approximately constant.Can be from moment t _zEquation (8) solve this value, this is the moment of electric current maximum constantly:

$\frac{{\mathrm{\&psi;}}_R\left(t\right)}{{\mathrm{\&tau;}}_r}\&ap;\frac{{\mathrm{\&psi;}}_R\left(t_z\right)}{{\mathrm{\&tau;}}_r}=u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{sdz}\_\max }---\left(13\right)$

By the integral expression with equation (13) substitution equation (12), can as follows the rotor flux according to index law be extrapolated to t constantly _z:

${\mathrm{\&psi;}}_R\left(r_z\right)=R_R{\mathrm{\&tau;}}_r{i}_{\mathrm{dc}\_\mathrm{magn}}{e}^{-{\mathrm{<figure-callout\; id="0"\; label="t\; z"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">t</figure-callout>}}_z/{\mathrm{\&tau;}}_r}+R_R\underset{t_{z0}}{\overset{t_z}{\&Integral;}}{i}_{\mathrm{sd}}\left(t\right)\mathrm{dt}---\left(14\right)$

$-(u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{sdz}\_\max })(t_z-t_{z0})$

Based on equation (14), should calculate rotor time constant, it is at moment t _zProvide the rotor flux with value identical with equation (9), that is:

$R_R{\mathrm{\&tau;}}_r{i}_{\mathrm{dc}\_\mathrm{magn}}{e}^{-(t_{z0}-t_0)/{\mathrm{\&tau;}}_r}+R_R\underset{t_{z0}}{\overset{t_z}{\&Integral;}}{i}_{\mathrm{sd}}\left(t\right)\mathrm{dt}-(u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{sdz}\_\max })(t_z-t_{z0})$

$=(u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{sdz}\_\max }){\mathrm{\&tau;}}_r$

$\&DoubleLeftRightArrow;R_R{\mathrm{\&tau;}}_r{i}_{\mathrm{dc}\_\mathrm{magn}}{e}^{-(t_{z0}-t_0)/{\mathrm{\&tau;}}_r}$

$=(u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{sdz}\_\max })({{\mathrm{\&tau;}}_r+t}_z-t_{z0})-R_R\underset{t_{z0}}{\overset{t_z}{\&Integral;}}{i}_{\mathrm{sd}}\left(t\right)\mathrm{dt}$

$\&DoubleRightArrow;{\mathrm{\&tau;}}_r=\frac{t_{z0}-{\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">t</figure-callout>}}_0}{\ln \left(\frac{R_R{\mathrm{\&tau;}}_r{i}_{\mathrm{dc}\_\mathrm{magn}}}{(u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{sdz}\_\max })({\mathrm{\&tau;}}_r+t_z-t_{z0})-R_R\underset{t_{z0}}{\overset{t_z}{\&Integral;}}{i}_{\mathrm{sd}}\left(t\right)\mathrm{dt}}\right)}---\left(15\right)$

As shown, can not solve more accurate rotor time constant from equation (15) in closing form.Yet, can use suitable alternative manner with its numerical value solve.Another kind may be to use the calculating valuation of rotor time constant on the right side of equation (15).For example can calculate this calculating valuation from the rated value of motor.Even rated value is slightly incorrect, calculates valuation in equation right side use and still produced than equation (11) valuation more accurately.

Calculate rotor time constant to need the resistance of stator and rotor be known from equation (11) or (15).The stator resistance that can measure with considerable accuracy during DC magnetization, but due to the Injection Signal that uses and frequency thereof, the rotor resistance valuation may have suitable error.Especially, error is by inaccurate the causing in kelvin effect and voltage measurement and/or voltage control.Due to the derivative of stator current at i _{Sdz_max}Neighbouring approaching zero, so error can also be owing to determining t constantly _zInaccurate.

Different delay t when using null vector by utilization _z01And t _z02The pulse test that repeats to carry out above can reduce the sensitiveness from the valuation of equation (11) and (15).Illustrate this process in Fig. 3.Therefore, carry out twice different test, wherein at first pass through current i _{Dc_max}Make motor magnetization and at moment t ₀Make pulse deopiking.The test 1 at moment t _z01Utilize null vector, after this stator current is according to curve i _sd1Flow and at moment t _z1Reach its maximum i _{Sdz_max1}The test 2 at t _z01The moment afterwards is namely at moment t _z02Activate null vector, this after-current is according to curve i _sd2Flow and at moment t _z2Reach its maximum i _{Sdz_max2}

According to equation (9), moment t _z1And t _z2Rotor flux be:

$\left\{\begin{array}{c}{\mathrm{\&psi;}}_R\left(t_{z1}\right)=(u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{sdz}\_\max 1}){\mathrm{\&tau;}}_r\\ {\mathrm{\&psi;}}_R\left(t_{z2}\right)=(u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{sdz}\_\max 2}){\mathrm{\&tau;}}_r\end{array}\right.---\left(16\right)$

If at period t _z1... t _z2Access failure null vector during this time, rotor flux will be decayed, and when pulse was passivated, the index law according to equation (10) made:

${\mathrm{\&psi;}}_R\left(t_{z2}\right)={\mathrm{\&psi;}}_R\left(t_{z1}\right)e^{-(t_{z2}-t_{z1})/{\mathrm{\&tau;}}_r}---\left(17\right)$

Can by carrying out identical approximate of situation with the valuation that utilizes equation (11), suppose at moment t now _z1And t _z2Can greatly the not slow down decay of rotor flux of the increase of the stator current during null vector before solves rotor time constant.In other words, satisfy equation group (16) according to the decay of the rotor flux (17) of index law, thus

$(u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{sdz}\_\max 2}){\mathrm{\&tau;}}_r=(u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{sdz}\_\max 1}){\mathrm{\&tau;}}_r{e}^{-(t_{z2}-t_{z1})/{\mathrm{\&tau;}}_r}$

$e^{-(t_{z2}-t_{z1})/{\mathrm{\&tau;}}_r}=\frac{u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{sdz}\_\max 2}}{u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{sdz}\_\max 1}}$

$\&DoubleRightArrow;{\mathrm{\&tau;}}_r=\frac{t_{z2}-t_{z1}}{\ln \left(\frac{u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{sdz}\_\max 1}}{u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{sdz}\_\max 2}}\right)}---\left(18\right)$

By comparison equation (11) and (18), see the rotor time constant valuation of calculating by equation (18) than the valuation from equation (11), significantly the less error that depends on resistance.Along with threshold voltage u _thReduce, the sensitiveness of this error to the resistance valuation reduces.In addition, in two rotor fluxs that calculate according to equation group (16), null vector is approximately equalised on value to the relative effect of the decay of rotor flux in equation (18).This means, in fact compensated mentioned impact in the business of the logarithmic function of equation (18).Therefore, when testing to calculate rotor time constant with two independent null vectors, do not need the impact of method considering zero vector as about equation (15).

In addition, in the situation from the valuation of equation (18), can avoid from really regularly carving t in the valuation of equation (11) and (15) _zInaccurate.This is owing to the following fact: the rise time (t of electric current _z1-t _z01And t _z2-t _z02) be actually identical.Therefore, the time difference t in equation (18) _z2-t _z1Can be by time difference t _z02-t _z01Replace.Because time difference of the latter is accurately known valuation, therefore

${\mathrm{\&tau;}}_r=\frac{t_{z02}-t_{z01}}{\ln \left(\frac{u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{sdz}\_\max 1}}{u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{sdz}\_\max 2}}\right)}---\left(19\right)$

Provided recently the valuation more accurate result from equation (18).

Therefore, according to the present invention, measure stator current during zero-voltage vectors, and determine the parameter of induction machine from measured stator current.

In the above-described embodiments, determined parameter is rotor time constant, and during null vector, has determined that also maximum current and the moment thereof are to be used for calculating.

According to embodiments of the invention, after the first test process, again make induction machine magnetization and utilize frequency converter shutdown and the null vector different period between connecting to repeat this test process.Reach time difference estimated rotor time constant between its peaked moment with electric current.Carry out therein in the preferred embodiments of the present invention of twice independent test, replace the time difference of maximum current between constantly with the time difference between the null vector switching time.As is understood, for the time difference between twice independent measurement, refer to the moment of point measurement from test separately, but not the time that disappears between test.

Rotor resistance and threshold voltage

In the embodiment that above explains of the present invention, estimated rotor time constant.In this was estimated, the parameter of using comprised rotor resistance and threshold voltage.Do not using these parameters that can provide in situation of the present invention for the estimated rotor time constant.Yet, the invention provides a kind of method than previously known and determine more accurately rotor resistance R _RWith threshold voltage u _thMethod.

Suppose to pass through current i _{Dc_magn}Make the motor magnetization until obtain stable state.As seen in Figure 4, remove pulse after magnetization, namely temporarily make the power stage passivation, and at moment t _z1Connect null vector, wherein electric current has dropped to value i _sd1Due to null vector, the decline of stator current at first stop and with after-current lentamente towards zero attenuation.In some cases, in Fig. 4, electric current increases temporarily, forms local maximum before it begins to descend.

By equation (3) as can be known, during null vector, the derivative of electric current is

$\frac{{\mathrm{di}}_{\mathrm{sd}}}{\mathrm{dt}}=\frac{1}{\mathrm{\&sigma;}{L}_s}(\frac{{\mathrm{\&psi;}}_R}{{\mathrm{\&tau;}}_r}-u_{\mathrm{th}}-(R_s+R_R)i_{\mathrm{sd}})$

Purpose is to find the extreme value i about stator current _sd0With corresponding connection moment t about null vector _z0, make the derivative of stator current of the right hand at moment t _z0Zero, namely

$\underset{t\&RightArrow;{\mathrm{<figure-callout\; id="0"\; label="t\; z"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">t</figure-callout>}}_z^0}{\lim }\left(\frac{{\mathrm{di}}_{\mathrm{sd}}}{\mathrm{dt}}\right)={\left(\frac{{\mathrm{di}}_{\mathrm{sd}}}{\mathrm{dt}}\right)}_{t={\mathrm{<figure-callout\; id="0"\; label="t\; z"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">t</figure-callout>}}_z^0}=0$

Subsequently, follow the connection of null vector closely constantly, following condition is set up:

${\left(\frac{{\mathrm{di}}_{\mathrm{sd}}}{\mathrm{dt}}\right)}_{t={\mathrm{<figure-callout\; id="0"\; label="t\; z"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">t</figure-callout>}}_z^0}=\frac{1}{\mathrm{\&sigma;}{L}_s}(\frac{{\mathrm{\&psi;}}_R\left(t_{z0}\right)}{{\mathrm{\&tau;}}_r}-u_{\mathrm{th}}-(R_s+R_R)i_{\mathrm{sd}0})=0---\left(21\right)$

Owing to working as electric current from i _{Dc_magn}Drop to i _sd0The time, in fact rotor flux does not change, therefore following approximate establishment:

ψ _R(t _z0)≈L _{Midc_magn}＝τ _rR _Ri _{dc_magn} (22)

By with equation (22) substitution equation (21), obtained

R _Ri _{dc_magn}-u _th-(R _s+R _R)i _sd0＝0 (23)

In other words, at moment t _z0The current limitation i of the zero derivative of generation current _sd0Value be

$i_{\mathrm{<figure-callout\; id="0"\; label="sd"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">sd</figure-callout>}0}=\frac{R_R{i}_{\mathrm{dc}\_\mathrm{magn}}-u_{\mathrm{th}}}{R_s+R_R}---\left(24\right)$

If electric current drops to this below limit before activating null vector, as in Fig. 4, be positive corresponding to the derivative of equation (21), t=t wherein _z1If in Fig. 5, again activate zero-voltage vectors, namely activate too early zero-voltage vectors, the electric current at switching time place is i _sd2＞i _sd0And the derivative of electric current is born.

If at moment t _z0Connect zero-voltage vectors, wherein electric current drops to the value that equation (24) provides exactly, the derivative of the stator current of switching time be zero and current waveform consistent with Fig. 6.

Therefore purpose is to find the current limitation i of the current waveform that produces Fig. 6 _sd0In fact, in order to find correct current value, must carry out a plurality of testing currents.Between test, the null vector switching time can change.Alternatively, can when dropping to the limit that sets, stator current utilize null vector.This limit also can change, and is used for obtaining correct current value, and the derivative of this current value constantly is zero connecting.

Be different from after magnetization and make the power stage passivation, if the connection that can set more accurately zero-voltage vectors is constantly, the voltage vector that can also force power stage to produce to have the direction opposite with the voltage vector of use during the DC magnetization.

Can search for relatively rapidly about connecting the extreme value that produces the electric current of zero derivative constantly.Can begin immediately the motor magnetization for next test after the electric current derivative that calculates null vector starting point place.Due to not too much decay of rotor flux during null vector, therefore the magnetizing time between test is also very short.The typical stator current waveforms of the searching period of zero derivative has been shown in Fig. 7.

Alternatively, from providing two current responses of positive derivative and negative derivative, can approximate current limit i _sd0If these current responses are as shown in Figures 4 and 5, can be by for example as follows, with derivative pro rata to current limitation i _sd1And i _sd2Weighting is from current limitation i _sd1And i _sd2Calculate the approximation of current limitation:

$i_{\mathrm{<figure-callout\; id="0"\; label="sd"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">sd</figure-callout>}0}\&ap;\frac{i_{\mathrm{sd}2}\left|{\left(\frac{{\mathrm{di}}_{\mathrm{sd}}}{\mathrm{dt}}\right)}_{t=t_{z1}^{+}}\right|+i_{\mathrm{sd}1}\left|{\left(\frac{{\mathrm{di}}_{\mathrm{sd}}}{\mathrm{dt}}\right)}_{t=t_{z2}^{+}}\right|}{\left|{\left(\frac{{\mathrm{di}}_{\mathrm{sd}}}{\mathrm{dt}}\right)}_{t=t_{z1}^{+}}\right|+\left|{\left(\frac{{\mathrm{di}}_{\mathrm{sd}}}{\mathrm{dt}}\right)}_{t=t_{z2}^{+}}\right|}---\left(25\right)$

When finding optimal current response and relevant current limitation i _sd0The time, can use the current limitation from equation (23) to calculate the rotor resistance valuation, it provides:

$R_R=\frac{u_{\mathrm{th}}+R_s{i}_{\mathrm{sd}0}}{i_{\mathrm{dc}\_\mathrm{magn}}-i_{\mathrm{sd}0}}---\left(26\right)$

The calculating of rotor resistance needs threshold voltage u _thWith stator resistance R _sKnown.The problem of equation (26) is that the value of threshold voltage is not necessarily accurately known.In addition, the value of threshold voltage greatly affects the accuracy of the valuation that can pass through equation (26) acquisition.Yet, if threshold voltage is known, can directly use equation (26).

Typically, in frequency converter, threshold voltage is be set to the parameter of steady state value or estimate threshold voltage during the DC magnetization.If the estimation threshold voltage, to postpone to make the threshold voltage valuation be not too accurately to the commutation in power stage, and if the threshold voltage u that therefore obtains from the DC magnetization _thBe placed in equation (26), the valuation of rotor resistance is also not too accurately.

Yet, can use equation (23) acquisition about the value more accurately (perhaps being used for the cancellation threshold voltage) of threshold voltage.In the situation that equation (23) is set up therein, null vector is activated, and electric current is uniform and it flows via power component, and the threshold voltage of these power components should be known in above equation.

The thinking of this estimation is to utilize no DC magnetizing current carry out above-described a plurality of null vector test and search for different magnetizing current i before making the power stage passivation _{Dc_magn, i}Current limitation i separately _{Sd0, i}, these current limitations are at the zero derivative of the connection moment of null vector generation current.Like this, regardless of the value of the magnetizing current that uses, equation (23) is set up.

For example, by using two different magnetizing currents, obtained a pair of equation:

$\left\{\begin{array}{c}{R}_R{i}_{\mathrm{dc}\_\mathrm{magn},1}=u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{<figure-callout\; id="0"\; label="sd"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">sd</figure-callout>}\mathrm{0,1}}\\ R_R{i}_{\mathrm{dc}\_\mathrm{magn},2}=u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{<figure-callout\; id="0"\; label="sd"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">sd</figure-callout>}0,2}\end{array}\right.---\left(27\right)$

And by cancellation threshold voltage u _th, rotor resistance can be calculated as the function of stator resistance:

$R_R=\frac{i_{\mathrm{<figure-callout\; id="0"\; label="sd"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">sd</figure-callout>}\mathrm{0,1}}-{\mathrm{<figure-callout\; id="0"\; label="i\; sd"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">i</figure-callout>}}_{\mathrm{sd}}}{(i_{\mathrm{dc}\_\mathrm{magn},1}-i_{\mathrm{dc}\_\mathrm{magn},2})-({\mathrm{<figure-callout\; id="0"\; label="i\; sd"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">i</figure-callout>}}_{\mathrm{sd}}-{\mathrm{<figure-callout\; id="0"\; label="i\; sd"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">i</figure-callout>}}_{\mathrm{sd}})}{R}_s---\left(28\right)$

Can also solve threshold voltage to (27) from equation, it provides:

$u_{\mathrm{th}}=\frac{(i_{\mathrm{dc}\_\mathrm{magn},1}-{\mathrm{<figure-callout\; id="0"\; label="i\; sd"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">i</figure-callout>}}_{\mathrm{sd}})i_{\mathrm{<figure-callout\; id="0"\; label="sd"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">sd</figure-callout>}\mathrm{0,2}}-(i_{\mathrm{dc}\_\mathrm{magn},2}-{\mathrm{<figure-callout\; id="0"\; label="i\; sd"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">i</figure-callout>}}_{\mathrm{sd}})i_{\mathrm{<figure-callout\; id="0"\; label="sd"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">sd</figure-callout>}\mathrm{0,1}}}{(i_{\mathrm{dc}\_\mathrm{magn},2}-{\mathrm{<figure-callout\; id="0"\; label="i\; sd"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">i</figure-callout>}}_{\mathrm{sd}})-(i_{\mathrm{dc}\_\mathrm{magn},1}-{\mathrm{<figure-callout\; id="0"\; label="i\; sd"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">i</figure-callout>}}_{\mathrm{sd}})}{R}_s---\left(29\right)$

Correspondingly, by using a plurality of different DC magnetizing currents, obtained a prescription journey

$\left\{\begin{array}{c}{i}_{\mathrm{dc}\_\mathrm{magn},1}=A+B{i}_{\mathrm{<figure-callout\; id="0"\; label="sd"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">sd</figure-callout>}\mathrm{0,1}}\\ i_{\mathrm{dc}\_\mathrm{magn},2}=A+B{i}_{\mathrm{<figure-callout\; id="0"\; label="sd"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">sd</figure-callout>}\mathrm{0,2}}\\ \&CenterDot;\&CenterDot;\&CenterDot;\\ i_{\mathrm{dc}\_\mathrm{magn},n}=A+B{i}_{\mathrm{<figure-callout\; id="0"\; label="sd"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">sd</figure-callout>}0,n}\end{array}\right.---\left(30\right)$

By using linear regression, can calculating and the proportional regression coefficient of threshold voltage and resistance ratio

$\left\{\begin{array}{c}A\&ap;\frac{u_{\mathrm{th}}}{R_R}\\ B\&ap;\frac{R_s+R_R}{R_R}\end{array}\right.---\left(31\right)$

And in addition, rotor resistance valuation and threshold voltage valuation can be calculated as the function of stator resistance.

$\left\{\begin{array}{c}{R}_R=\frac{R_s}{(B-1)}\\ u_{\mathrm{th}}=\frac{A{R}_s}{(B-1)}\end{array}\right.---\left(32\right)$

Measure owing to utilizing a plurality of measurement points to carry out, therefore basically more accurate than the valuation that obtains by equation (28) and (29) by the valuation of (32) acquisition.

Estimated threshold voltage and rotor resistance can be identified individually and these valuations need to not used in embodiment given above.

The rotor time constant of cache oblivious

In above-described embodiment of estimated rotor time constant, stator and rotor resistance and be assumed to be known (equation (11), (15), (18) and (19)).In addition, equation (11) and (15) need rotor resistance as independent parameter.When the valuation of the rotor resistance that obtains by the above embodiment of the present invention or by some other modes and threshold voltage was placed in equation mentioned above, stator resistance was still unknown parameter.Can easily measure the stator resistance as the ratio between voltage and current during the DC magnetization.Yet typically by the dc voltage of intermediate circuit and determined by the output switch combination, the stator resistance of therefore measuring by this mode has certain uncertainty due to the average output voltage of frequency converter.

Because commutation postpones and the uncertainty of the threshold voltage compensation of power stage, the output voltage of frequency converter may be slightly inaccurate.Therefore because the voltage that is fed to motor is little, should inaccurately has during DC magnetizes and seriously influenced.This can be regarded as the error of the stator resistance of identification during DC magnetization, and in addition, if calculate rotor time constant based on stator resistance, can also be regarded as the error of rotor time constant.

When the embodiment of combination estimated rotor time constant mentioned above, rotor resistance and threshold voltage, can be almost and any cache oblivious ground calculating rotor time constant.In this embodiment of the present invention, carry out twice independent null vector test.In the first test (Fig. 8, test 1), pass through current i _{Dc_magn1}Make the motor magnetization until obtain stable state.Subsequently at moment t ₀Remove pulse and at moment t _z0Start null vector.Due to null vector, electric current begins to increase and at moment t _zReach local maximum i _{Sdz_max}

After the first test, carry out the second stage of this embodiment.In second stage (test 2), determine that in conjunction with being used for the embodiment of rotor time constant and threshold voltage carries out similar null vector test.In this case, use the DC current i _{Dc_magn2}Make the motor magnetization, after this at moment t ₀Remove pulse (making the power stage passivation).When electric current drops to the local maximum i that obtains in test 1 _{Sdz_max}Level the time, activate null vector.Test 2 purpose is, when making the motor magnetization by mentioned electric current and in the situation that electric current activates null vector when being in the level of mentioned local maximum, finding to make current response have the magnetizing current i of zero derivative _{Dc_magn2}

By using above-described method be used to finding zero derivative (Fig. 4 to 7), make i _sd0Be replaced by i _{Sdz_max}, can search for suitable magnetizing current.Yet, in this case, be different from current limitation i _sd0, magnetizing current is changed.For example, in the situation of Fig. 4, magnetizing current should reduce, and in the situation of Fig. 5, magnetizing current should increase.

When the magnetizing current of the zero derivative that produces stator current is found, according to equation (23)

R _Ri _{dc_magn2}＝u _th+(R _s+R _R)i _{sdz_max} (33)

When equation (33) (is made i by substitution equation (11) _{Dc_magn}Be replaced by i _{Dc_magn1}) time, obtained the valuation about rotor time constant:

$\&DoubleRightArrow;{\mathrm{\&tau;}}_{\mathrm{\&rho;}}=\frac{{\mathrm{\&tau;}}_{\mathrm{\&zeta;}}-{\mathrm{\&tau;}}_0}{\mathrm{\&lambda;\&nu;}\left(\frac{{\mathrm{\&iota;}}_{\mathrm{\&delta;\&chi;}\_\mathrm{\&mu;\&alpha;\&gamma;\&nu;}1}}{{\mathrm{\&iota;}}_{\mathrm{\&delta;\&chi;}\_\mathrm{\&mu;\&alpha;\&gamma;\&nu;}2}}\right)}---\left(34\right)$

As can be seen, in the formula according to equation (34), it is known that the parameter of electric machine needs not be.Due to similar equation (11), equation (34) is not considered period t _z0... t _zThe increase of the stator current the during decay of rotor flux during this time, so this formula comprises little error.This error depends on the parameter of electric machine, and on this meaning, equation (34) the also incomplete and parameter of electric machine has nothing to do.

Introduced consideration period t in equation (15) _z0... t _zThe valuation more accurately of the increase of stator current during this time.Also can use same equation in conjunction with the present embodiment., obtained during by substitution equation (15) when equation (33):

$\&DoubleRightArrow;{\mathrm{\&tau;}}_r=\frac{t_{z0}-{\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">t</figure-callout>}}_0}{\ln \left(\frac{{\mathrm{\&tau;}}_r{i}_{\mathrm{dc}\_\mathrm{magn}1}}{i_{\mathrm{dc}\_\mathrm{magn}2}({\mathrm{\&tau;}}_r+t_z-t_{z0})-\underset{t_{z0}}{\overset{t_z}{\&Integral;}}{i}_{\mathrm{sd}}\left(t\right)\mathrm{dt}}\right)}---\left(35\right)$

Similar equation (34), equation (35) is without any need for the parameter of electric machine.By using equation (35), can obtain the valuation more accurately of rotor time constant.On the other hand, the problem relevant to equation (35) be, rotor time constant be exist with implicit form and for it is solved, need iteration.Yet, by in the logarithmic function with the front valuation substitution equation right-hand side that once calculates always, easily untied this equation by iterative algorithm.Because the right-hand side of equation is not highly to depend on the rotor time constant that uses in the independent variable of logarithmic function, so iteration very rapidly restrains.

In theory, if the L equivalent electric circuit represents the behavioral characteristics of motor exactly, valuation and other parameters of electric machine of equation (35) generation are fully irrelevant.In fact, at moment t ₀Iron loss is sizable on the impact of electric current derivative, and therefore provides the magnetizing current i of zero derivative _{Dc_magn2}The magnetizing current that should obtain in the time of may being different from the calculation of parameter of using the L equivalent electric circuit.

For this reason, preferably, as pointing out in Fig. 9, carry out twice null vector test, make pulse deopiking before this in certain period, make when null vector is activated electric current always zero.These the test basically with Fig. 3 in test similar.Yet the thinking in this situation is to use as follows two different magnetizing current i _{Dc_magn1}And i _{Dc_magn2}: the maximum of the stator current during null vector equates on value.In other words, in Fig. 9, i _{Sdz_max1}=i _{Sdz_max2}=i _{Sdz_max}Due in the situation of Fig. 9, t _z02＞t _z01So in test 2, magnetizing current i _{Dc_magn2}Must be higher than magnetizing current i _{Dc_magn1}Thereby, compensation period t _z01... t _z02The decay of rotor flux during this time.

By the hypothesis rotor flux based on equation (12) from moment t ₀To moment t _z1And t _z2According to same index law decay, obtained

$\left\{\begin{array}{c}{L}_M{i}_{\mathrm{dc}\_\mathrm{magn}1}{e}^{-(t_{z1}-t_0)/{\mathrm{\&tau;}}_r=(u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{sdz}\_\max })}{\mathrm{\&tau;}}_r-R_R\underset{t_{z01}}{\overset{t_{z1}}{\&Integral;}}{i}_{\mathrm{sd}1}\left(t\right)\mathrm{dt}\\ L_M{i}_{\mathrm{dc}\_\mathrm{magn}2}{e}^{-(t_{z2}-t_0)/{\mathrm{\&tau;}}_r}=(u_{\mathrm{th}}+(R_s+R_R)i_{\mathrm{sdz}\_\max }){\mathrm{\&tau;}}_r-R_R\underset{t_{z02}}{\overset{t_{z2}}{\&Integral;}}{i}_{\mathrm{sd}2}\left(t\right)\mathrm{dt}\end{array}\right.---\left(36\right)$

Current impulse during null vector is identical, and therefore

$\underset{t_{z01}}{\overset{t_{z1}}{\&Integral;}}{i}_{\mathrm{sd}1}\left(t\right)\mathrm{dt}=\underset{t_{z02}}{\overset{t_{z2}}{\&Integral;}}{i}_{\mathrm{sd}2}\left(t\right)\mathrm{dt}$

Equation has identical value to the right-hand side of (36), and has obtained

$L_M{i}_{\mathrm{dc}\_\mathrm{magn}1}{e}^{-(t_{z1}-t_0)/{\mathrm{\&tau;}}_r}=L_M{i}_{\mathrm{dc}\_\mathrm{magn}2}{e}^{-(t_{z2}-t_0)/{\mathrm{\&tau;}}_r}---\left(37\right)$

If work as magnetizing current from i _{Dc+_magn1}Be increased to i _{Dc_magn2}The time main inductance unsaturation, it is divided out from equation (37), making rotor time constant is unique the unknown.

Can followingly solve rotor time constant from equation (37):

$i_{\mathrm{dc}\_\mathrm{magn}1}{e}^{-(t_{z1}-t_0)/{\mathrm{\&tau;}}_r}=i_{\mathrm{dc}\_\mathrm{magn}2}{e}^{-(t_{z2}-t_0)/{\mathrm{\&tau;}}_r}$

$\&DoubleLeftRightArrow;e^{(t_{z2}-t_{z1})/{\mathrm{\&tau;}}_r}=\frac{i_{\mathrm{dc}\_\mathrm{magn}2}}{i_{\mathrm{dc}\_\mathrm{magn}1}}$

$\&DoubleLeftRightArrow;{\mathrm{\&tau;}}_r=\frac{t_{z2}-t_{z1}}{\ln \left(\frac{i_{\mathrm{dc}\_\mathrm{magn}2}}{i_{\mathrm{dc}\_\mathrm{magn}1}}\right)}---\left(38\right)$

Accordingly, in a preferred embodiment, at first by magnetizing current i _{Dc_magn1}Make the motor magnetization.The magnetization after at moment t ₀The switch of frequency converter is controlled to be not on-state.At moment t _z01Controlling frequency converter generation null vector and stator current begins to rise.At moment t _z1Stator current reaches its maximum i _{Sdz_max1}And begin decay.

Use different magnetizing current i _{Dc_magn2}Motor is magnetized again and the process of duplication similarity.Purpose is to find magnetizing current and the corresponding time constant when utilizing null vector, and its generation has the peaked stator current that obtains corresponding in the phase I of testing.

May must search for desired magnetizing current by the second stage of retest.Magnitude variations by making magnetizing current or the moment of utilizing null vector is changed can change the maximum of the stator current during null vector.Figure 9 illustrates the second magnetizing current i _{Dc_magn2}Higher than the first magnetizing current i _{Dc_magn1}Yet the operation of this embodiment does not need at first to use lower electric current.Unique requirement about electric current is that electric current has different values.

In case find the peaked moment of the stator current during the second magnetizing current and null vector, can use equation (38) to calculate rotor time constant, the peaked moment of wherein also using the value of the first magnetized magnetizing current and the stator current during the phase I.

Because the current impulse during null vector is identical, therefore following condition is set up:

t _z1-t _z01＝t _z2-t _z02

Therefore in equation (38), can differ from t service time _z02-t _z01Replace time difference t _z2-t _z1, caused

${\mathrm{\&tau;}}_r=\frac{t_{z02}-t_{z01}}{\ln \left(\frac{i_{\mathrm{dc}\_\mathrm{magn}2}}{i_{\mathrm{dc}\_\mathrm{magn}1}}\right)}---\left(39\right)$

Due to than the time difference between maximum current, can determine more exactly the time difference between the connection constantly of null vector, therefore provided than equation (38) result more accurately from the valuation of the rotor time constant of equation (39).

By inferring at moment t ₀+ t _z02-t _z01Last test in rotor flux ψ _R2Must equal first the test at moment t ₀Rotor flux ψ _R1, can also obtain equation (39) by more direct mode.This is owing to the following fact, equal the period (=t at these after constantly _z01) expire and connect null vector afterwards, and their generations have the current impulse of same value exactly.

Therefore, can infer that following relation sets up and directly cause equation (39)

${\mathrm{\&psi;}}_{R1}\left(t_0\right)={\mathrm{\&psi;}}_{R2}({\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="HSA00000192376700012.png,HSA00000192376700021.png"\; state="\{\{state\}\}">t</figure-callout>}}_0+t_{z02}-t_{z01})={\mathrm{\&psi;}}_{R2}\left(t_0\right)e^{-(t_{z02}-t_{z01})/{\mathrm{\&tau;}}_r}$

${\&DoubleLeftRightArrow;L}_M{i}_{\mathrm{dc}\_\mathrm{magn}1}=L_M{i}_{\mathrm{dc}\_\mathrm{magn}2}{e}^{-(t_{z02}-t_{z01})/{\mathrm{\&tau;}}_r}---\left(40\right)$

Main inductance

Can calculate long-pending main inductance L as rotor time constant and rotor resistance from the valuation that obtains by embodiments of the invention _M, namely

L _M＝R _Rτ _r (41)

Because rotor time constant and the rotor resistance estimated by method of the present invention are also accurately, the main inductance that therefore calculates by equation (41) is accurately.

Control system

Figure 10 shows the example of the control system that can be used for implementing method of the present invention.This control system is to use between the mode by the expected of being used for is controlled error-free running period of frequency converter of motor.This control system produces the control signal for the power stage of frequency converter.Control the modulation scheme of motor in this control signal of modulator calculating of frequency converter according to being used for.

In Figure 10, the modulator that control system comprises current controller, voltage controller and operates in the dq coordinate system.During the DC magnetization, current controller output voltage benchmark, this current controller basis is about magnetizing current i _{Dc_magn}Benchmark control the d component of electric current, and correspondingly the q component of electric current is controlled to be zero.By these control actions, force current vector to be on the direction of angle θ, this direction has provided the direction of magnetization and has therefore provided the direction of d axle.Voltage reference is transformed in the stator reference system and is fed to voltage controller and further is fed to the modulator of power ratio control level.Be connected to the induction machine generation current response of frequency converter, based on the direction of measured phase current with magnetization θ, this current response transformed in the dq coordinate system.Preferably, angle θ is selected as being on the direction of phase place of induction machine, but also can at random be selected.

Can use this control system in conjunction with above-described definite rotor time constant as follows.At moment t=t ₀(seeing Fig. 2), identification module is by being set as parameter m od_ena the power stage passivation that vacation (False) makes frequency converter, this is off status and when the terminal voltage of motor is set as the voltage of inducting by the decay of rotor flux with the output switch components set, and phase current is set as zero.At moment t=t _z0, identification module activates power stage and by parameter m od_ena and zero_force are set as very (True), forces the use zero-voltage vectors.During zero-voltage vectors, identification module is determined current i according to equation (11) _sdMaximum (i _{Sdz_max}) and moment t _z, be used for determining rotor time constant.

Can similarly implement other embodiment of the present invention by the control system of Figure 10 by sequential control enable signal zero_force and mod_ena.Signal zero_force forces and utilizes null vector (moment t _z0, t _z01And t _z02) and signal mod_ena make power stage passivation (t constantly ₀).In the example of Figure 10, arrange null vector by providing voltage reference to modulator.Alternatively, also can utilize null vector and not use illustrated voltage reference in Figure 10 by direct control output switch element.

Describe in detail in conjunction with different embodiment as mentioned, different embodiment of the present invention may need DC magnetization, power stage passivation and the null vector of different number of times to force application.Recognition logic module in Figure 10 is paid close attention to the various signals of controlling process of the present invention and the value of monitoring stator current and derivative thereof, is used for obtaining about i _{Sdz_max}, i _{Sdz_max1}, i _{Sdz_max2}, i _sd, t _z, t _z1And t _z2Value.These values are notified to parameter calculating module by signal, and this parameter calculating module is used the various equations that are used for calculating as described in detail above desired parameters.

Above-mentioned control system has pointed out to calculate all above-mentioned parameters.Yet some parameters do not need to estimate with method of the present invention, and some parameters can be estimated with other method.

Be apparent that for those skilled in the art, along with technological progress, concept of the present invention can realize by variety of way.The present invention and embodiment are not limited to above-described example, but can change within the scope of the claims.

Claims (17)

1. one kind is connected at induction machine the method for identifying the parameter of described induction machine when the output phase of voltage source frequency converter and described induction machine are in stop state, it is characterized in that,

Provide direct current DC magnetizing current (i by described frequency converter to described induction machine _{Dc_magn}),

The power semiconductor of described frequency converter is controlled to be off status,

Output is phased is made as same current potential with all of described frequency converter, is used for providing zero-voltage vectors,

Measure the stator current (i during described zero-voltage vectors _sd), and

From the stator current (i that measures during described zero-voltage vectors _sd) determine the parameter of described induction machine.

2. method as claimed in claim 1, is characterized in that, the parameter of identifying is rotor time constant (τ _r), wherein,

Described measurement stator current (i _sd) comprise the maximum current (i that measures during described zero-voltage vectors _{Sdz_max}) and the moment (t _z) step,

Determine rotor time constant (τ from following parameter _r):

DC magnetizing current (i _{Dc_magn}) value,

Resistance (the R of the stator of described motor and rotor _s, R _R),

Determined maximum current (i _{Sdz_max}) and the moment (t _z),

Described power semiconductor is controlled to be the moment (t of off status ₀), and

Threshold voltage (the u of described frequency converter _th).

3. method as claimed in claim 1, is characterized in that, the parameter of identifying is rotor time constant (τ _r), wherein,

Described measurement stator current comprises the maximum current (i during the described zero-voltage vectors of measurement _{Sdz_max}) and the moment (t _z) step,

Use iterative algorithm to determine rotor time constant from following parameter values ground:

DC magnetizing current (i _{Dc_magn}) value,

Resistance (the R of the stator of described motor and rotor _s, R _R),

Determined maximum current (i _{Sdz_max}) and the moment (t _z),

Utilize the moment (t of described zero-voltage vectors _z0),

Described power semiconductor is controlled to be the moment (t of off status ₀),

Threshold voltage (the u of described frequency converter _th), and

The initial valuation of rotor time constant.

4. method as claimed in claim 1, is characterized in that, the parameter of identifying is rotor time constant (τ _r), wherein,

Described measurement stator current comprises measures maximum current (i _{Sdz_max}) and the moment (t _z),

Utilization is about the different connection moment (t of described zero-voltage vectors _z01, t _z02), use same magnetizing current (i _{Dc_magn}) repeat the measurement of described maximum current,

Determine rotor time constant from following parameter:

The moment (the t of measured maximum current _z1, t _z2),

Measured maximum current (i _{Sdz_max1}, i _{Sdz_max2}),

Resistance (the R of the stator of described motor and rotor _s, R _R), and

Threshold voltage (the u of described frequency converter _th).

5. method as claimed in claim 1, is characterized in that, the parameter of identifying is rotor time constant (τ _r), wherein,

Described measurement stator current comprises measures maximum current (i _{Sdz_max}),

Utilization is about the different connection moment (t of described zero-voltage vectors _z01, t _z02), use same magnetizing current (i _{Dc_magn}) repeat the measurement of described maximum current,

Determine rotor time constant from following parameter:

The connection moment (t about zero-voltage vectors _z01, t _z02),

Measured maximum current (i _{Sdz_max1}, i _{Sdz_max2}),

Resistance (the R of stator and rotor _s, R _R), and

Threshold voltage (the u of described frequency converter _th).

6. method as claimed in claim 1, is characterized in that, the parameter of identifying is the rotor resistance (R of described motor _R), wherein,

Described output with described frequency converter is phased to be made as same current potential and to comprise the steps: wherein to be made as same current potential with described output is phased, makes the stator current (i that follows closely after switch _sd) derivative be zero, and

Described measurement stator current (i _sd) be included in the step that switch is measured stator current afterwards immediately, wherein from following calculation of parameter rotor resistance (R _R):

Measured stator current (i _sd0),

Magnetizing current (i _{Dc_magn}) value,

Threshold voltage (the u of described frequency converter _th), and

Stator resistance (the R of described motor _s).

7. method as claimed in claim 1, is characterized in that, the parameter of identifying is the rotor resistance (R of described motor _R), wherein,

Describedly be made as same current potential and comprise the steps: wherein to be made as same current potential with described output is phased described output is phased, make the stator current (i that follows closely after switch _sd) derivative be zero,

Described measurement stator current is included in the step that switch is measured stator current afterwards immediately, and

Utilize different magnetizing current (i _{Dc_magn, 1}, i _{Dc_magn, 2}, i _{Dc_magn, n}) make described step repeat one or many, be used for obtaining two or more stator current value (i _Sd0,1, i _Sd0,2, i _{Sd0, n}) and magnetizing current (i _{Dc_magn, 1}, i _{Dc_magn, 2}, i _{Dc_magn, n}) value,

Wherein from following calculation of parameter rotor resistance:

Measured stator current (i _Sd0,1, i _Sd0,2, i _{Sd0, n}),

Magnetizing current (i _{Dc_magn, 1}, i _{Dc_magn, 2}, i _{Dc_magn, n}) value, and

Stator resistance (the R of described motor _s).

8. method as claimed in claim 1, is characterized in that, the parameter of identifying is the threshold voltage (u of described frequency converter _th), wherein,

Describedly be made as same current potential and comprise the steps: wherein to be made as same current potential with described output is phased described output is phased, making the derivative that follows the stator current after switch closely is zero, and

Described measurement stator current is included in the step of measuring immediately stator current after switch, wherein from the threshold voltage of the described frequency converter of following calculation of parameter:

Measured stator current (i _sd0),

Magnetizing current (i _{Dc_magn}) value,

Rotor resistance (the R of described motor _R), and

Stator resistance (the R of described motor _s).

9. method as claimed in claim 1, is characterized in that, the parameter of identifying is the threshold voltage (u of described frequency converter _th), wherein,

Describedly be made as same current potential and comprise the steps: wherein to be made as same current potential with described output is phased described output is phased, making the derivative that follows the stator current after switch closely is zero,

Described measurement stator current is included in the step that switch is measured stator current afterwards immediately, and

Utilize different magnetizing currents to make described step repeat one or many, be used for obtaining two or more stator current value (i _Sd0,1, i _Sd0,2, i _{Sd0, n}) and magnetizing current (i _{Dc_magn, 1}, i _{Dc_magn, 2}, i _{Dc_magn, n}) value,

Wherein from the threshold voltage of the described frequency converter of following calculation of parameter:

Measured stator current (i _Sd0,1, i _Sd0,2, i _{Sd0, n}),

Magnetizing current (i _{Dc_magn, 1}, i _{Dc_magn, 2}, i _{Dc_magn, n}) value, and

Stator resistance (the R of described motor _s).

10. method as claimed in claim 1, is characterized in that, the parameter of identifying is rotor time constant, wherein,

Described measurement comprises the maximum current (i during the described zero-voltage vectors of measurement _{Sdz_max}) and the moment (t _z) step,

Described method is further comprising the steps:

A) provide the DC magnetization by the second magnetizing current to described induction machine,

B) the described power semiconductor with described frequency converter is controlled to be off status,

C) drop to measured lowest high-current value (i when stator current _{Sdz_max}) time, output is phased is made as same current potential with all of described frequency converter, and be used for providing zero-voltage vectors, and determine to follow closely the derivative of controlling the stator current after output switch,

If the derivative of determined stator current is not zero, change the second magnetizing current (i _{Dc_magn, 2}) value and repeat above step a), b) and c),

From following calculation of parameter rotor time constant:

Maximum current (the i of the stator current during described zero-voltage vectors _{Sdz_max}) the moment (t _z),

Described power semiconductor is controlled to be the moment (t of off status ₀),

Produce measured maximum current (i _{Sdz_max}) magnetization in the magnetizing current (i that uses _{Dc_magn, 1}) value, and

Produce the second magnetizing current (i of the zero derivative of stator current _{Dc_magn, 2}) value.

11. method as claimed in claim 1 is characterized in that, the parameter of identifying is rotor time constant, wherein,

Described measurement comprises the maximum current (i during the described zero-voltage vectors of measurement _{Sdz_max}) and the moment (t _z) step,

Described method is further comprising the steps:

A) provide the DC magnetization by the second magnetizing current to described induction machine,

B) the described power semiconductor with described frequency converter is controlled to be off status,

C) when stator current drops to the value of measured maximum current, output is phased is made as same current potential with all of described frequency converter, and be used for providing zero-voltage vectors, and determine to follow closely the derivative of controlling the stator current after output switch,

If the derivative of determined stator current is not zero, change the second magnetizing current (i _{Dc_magn, 2}) value and repeat above step a), b) and c),

From following calculation of parameter rotor time constant:

The connection that described zero-voltage vectors is activated is (t constantly _z0)

The moment (the t of the maximum current of the stator current during described zero-voltage vectors _z),

Described power semiconductor is controlled to be the moment (t of off status ₀),

Produce measured maximum current (i _{Sdz_max}) magnetization in the magnetizing current (i that uses _{Dc_magn, 1}) value,

Produce the second magnetizing current (i of the zero derivative of stator current _{Dc_magn, 2}) value, and

The initial value of rotor time constant.

12. the method as claim 11 is characterized in that, the rotor time constant that use is calculated calculates rotor time constant iteratively as the initial value of the rotor time constant in iteration.

13. as the described method of arbitrary claim in claim 1 to 12, it is characterized in that, after magnetization, the power semiconductor that is different from described frequency converter is controlled to be off status, described power semiconductor is controlled to be produces the voltage vector with polarity opposite with the voltage vector of use in magnetization.

14. method as claimed in claim 1 is characterized in that, the parameter of identifying is rotor time constant, wherein,

Described measurement comprises the maximum current (i during the described zero-voltage vectors of measurement _{Sdz_max}) and the moment (t _z1) step,

Described method is further comprising the steps:

A) by the second magnetizing current (i _{Dc_magn, 2}) provide the DC magnetization to described induction machine,

B) power semiconductor with described frequency converter is controlled to be off status,

C) output is phased is made as same current potential with all of described frequency converter, is used for providing zero-voltage vectors, and measures the maximum of the stator current during described zero-voltage vectors and (t constantly thereof _z2)

If the maximum of stator current is not equal to the maximum current (i that measures during the first magnetization _{Sdz_max}), change the second magnetizing current (i _{Dc_magn, 2}) value and repeat above step a), b) and c),

From following calculation of parameter rotor time constant:

Maximum current (the i of the stator current during described zero-voltage vectors _{Sdz_max}) the moment (t _z1, t _z2),

Produce measured maximum current (i _{Sdz_max}) magnetization in the magnetizing current (i that uses _{Dc_magn, 1}) value, and

Generation has the second magnetizing current (i that equals the described first magnetized peaked stator current _{Dc_magn, 2}) value.

15. the method as claim 14 is characterized in that, when calculating rotor time constant, has used the moment (t that utilizes zero-voltage vectors _z01, t _z02), but not the moment (t of maximum current _z1, t _z2).

16. the method as claims 14 or 15 is characterized in that, is different from the value that changes magnetizing current, changes the moment utilize described zero-voltage vectors, is used for obtaining to have the peaked stator current of the value that equals the maximum current measured during the first magnetization.

17. one kind is connected at induction machine the device of identifying the parameter of described induction machine when the output phase of voltage source frequency converter and described induction machine are in stop state, it is characterized in that,

Frequency converter is configured to provide direct current DC magnetization to described induction machine, and described device comprises:

Be used for the power semiconductor of described frequency converter is controlled to be the parts of off status,

Be used for being made as same current potential being used for providing the parts of zero-voltage vectors with all outputs of described frequency converter are phased,

Be used for measuring the parts of the stator current during described zero-voltage vectors, and

The stator current that is used for measuring during described zero-voltage vectors is determined the parts of the parameter of described induction machine.

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